Preparation of enriched extracts from Mentha longifolia subsp. typhoides samples collected from different localities...

In this study, the phytochemical profile of Mentha longifolia subsp. typhoides, a member of the Lamiaceae family with recognized medicinal and economic value, was investigated. The primary objective was to determine the optimal extraction conditions for triterpenic compounds, particularly ursolic acid (UA) and oleanolic acid (OA), and to prepare enriched extracts. To this end, 17 plant samples collected from 14 different localities in Eastern Türkiye were extracted using solvents of varying polarity (petroleum ether, dichloromethane, dichloromethane: acetone 9:1, acetone, ethyl acetate, ethanol, and 2% sodium hydroxide: ethanol) through maceration. GC-MS analyses revealed that dichloromethane and ethanol extracts were particularly rich in ursolic and oleanolic acids. LC-MS/MS results further demonstrated that ethanol extracts contained rosmarinic acid at a level of 67.31 mg/g extract, along with high concentrations of polyphenolic compounds such as acacetin, naringenin, and cynaroside. Among the solvents tested, ethanol yielded the highest extraction efficiency (6.70%), leading to the determination of optimal extraction conditions as 35 °C and pH 7 under these conditions, the 17 plant samples were fractionated into root, stem, leaf, and flower parts, and extracted with ethanol via maceration. GC-MS and TLC analyses indicated that the bioactive compounds were predominantly concentrated in the leaf and flower tissues. In the second phase of the study, based on GC-MS data, samples from the four richest localities were collected at different vegetative stages (pre-flowering, flowering, and post-flowering) and extracted under optimized conditions. The highest total triterpenic acid content (ursolic + oleanolic acids), amounting to 609.68 mg/g extract, was detected in the BH-5 (Mentha longifolia, Türkiye: Mardin, Nusaybin), flower extract collected from the Mardin-Beyazsu locality. Overall, the species was found to be rich in these compounds throughout its vegetative cycle, with the highest levels observed post-flowering. Additionally, PCA-based evaluation of soil elemental composition revealed an associative pattern between elevated Cu and Na concentrations and increased ursolic and oleanolic acid accumulation in plant tissues. These findings suggest that soil composition may contribute to triterpenoid distribution and underscore the potential of this species as a valuable natural resource for the cosmetic industry.